Editing Constraint satisfaction (section)

===Constraint logic programming===
{{main|Constraint logic programming}}

A constraint logic program is a [[Logic programming|logic program]] that contains constraints in the bodies of clauses. As an example, the clause <code>A(X):-X>0,B(X)</code> is a clause containing the constraint <code>X>0</code> in the body. Constraints can also be present in the goal. The constraints in the goal and in the clauses used to prove the goal are accumulated into a set called [[constraint store]]. This set contains the constraints the interpreter has assumed satisfiable in order to proceed in the evaluation. As a result, if this set is detected unsatisfiable, the interpreter backtracks. Equations of terms, as used in logic programming, are considered a particular form of constraints, which can be simplified using [[unification (computing)|unification]]. As a result, the constraint store can be considered an extension of the concept of [[substitution (logic)|substitution]] that is used in regular logic programming. The most common kinds of constraints used in constraint logic programming are constraints over integers/rational/real numbers and constraints over finite domains.

[[Concurrent constraint logic programming]] languages have also been developed. They significantly differ from non-concurrent constraint logic programming in that they are aimed at programming [[concurrent process]]es that may not terminate. [[Constraint handling rules]] can be seen as a form of concurrent constraint logic programming, but are also sometimes used within a non-concurrent constraint logic programming language. They allow for rewriting constraints or to infer new ones based on the truth of conditions.